Dear Ankita,
The fellow member (Ms. Sapana) has clearly explained the LTA points (process, criteria, limitation, etc.). I would like to add why your seniors are looking for tax exemption only on LTA. Though LTA is a very good and acceptable mode of tax exemption, there could be more options. Have you considered those points as well?
Additional Clarifications on LTA
The exemption is restricted to only two surviving children (unless, of course, the second birth has resulted in multiple children like twins or triplets).
LTA covers travel for yourself and your family. Family, in this case, includes yourself, parents, siblings dependent on you, spouse (even if your spouse is working), and children.
If your family travels without you, no LTA can be claimed. You have to make the trip.
LTA is not related to when you started your employment. The government fixes blocks of years. These blocks are as per calendar years (January 1 to December 31). The current block period is between 2014-2017 (as stated by Ms. Sapana as well).
Generally, in a block period, for tax exemption, an employee is entitled to two LTA claims. In most cases, the tax exemption is allowed only against the submission of proofs, which seems justified. Otherwise, how will you calculate the traveling amount only? (In our company, the travel proof is a must for tax exemption). Though the employee can claim the LTA as per his/her requirement, the tax exemption will be allowed only for two claims in a block period. The amount of the excess journey (beyond two) will be countable for Income Tax in the F.Y.
The employee can claim two years' LTA in a year and can submit adequate proofs to get tax exemption. If the proofs are lower than the LTA amount, then the balance will be countable for taxable income in the F.Y.
But you cannot claim two years' separate journeys in one year. This means the proofs must be related to one journey to get tax exemption in a single claim.
One LTA can be carried forward into the next block period (for tax exemption), but it needs to be claimed in the first year of the next block period. For example, if you do not take your LTA in 2014-17, or you avail only one LTA, then you will be able to take the pending LTA in 2018. This means, in the 2018-2021 block, you will be entitled to three journeys.
Even if you switch jobs, you can get the LTA not only from your present organization but also from your former employer if the concession is lying unutilized for the block period.
The LTA can be claimed only if you applied for leave and have actually traveled. There are two separate processes for taking LTA and availing of the tax benefits. To take the amount in advance, the employee needs to apply in the LTA Advance Form. To avail of the tax exemption, the employee needs to submit an LTA declaration. The declaration should comprise family details (as per eligibility, who took the journey), traveling cost, and related traveling bills.
In case both you and your spouse are working, if you claim any LTA journey, then your spouse will not be able to claim the same holiday traveling cost from his/her employer unless, of course, you go for another holiday and he/she claims it.
Last but not least, I would like to suggest you do homework to refine the points (my points and Ms. Sapana's points). Some points may have been repeated, or there may be some contradictions. The material is too long; you need to re-draft it to frame a proper policy.
I have also taken the points from the site itself but tried my best to narrate it properly and not to repeat the points as suggested by Ms. Sapana.
I think it is more than enough to cover the topic.